Tube expander



Aug. 2s, 192s.

R. BUNGEROTH TUBE EXPANDER Filed July 23, 1927 5 Sheets-Sheet 2 ngz Br /f/s mmf/firs Aug. 28, 1928. 1,682,724

R. vBuNGERo-rl-l TUBE EXPANDER Filed July 23, 192'?A 3 sheets-sheet 3 Eig.

WW l Patented Aug. v28, 1928.

lJNlTED ST'I'ES RUDOLF BUNGEROTH, 0F DUSSELDORF, GERMANY.

TUBE EXPANDER.

Application led July 23, 1927, Serial No. 208,013, and in Germany December 29, 1925.

The invention relates to apparatus for expanding metal tubes with regular or varying thickness of wall.

The expanding of tubes by inclined roller devices -by the use of a mandrel has been several times attempted. rlhe arrangements hitherto preferably used, in which the inandrel-shafts are subjected to pressure, have given rise to considerable difculties since the mandrel subjected to pressure, yields more or less in accordance with the degree of the rolling pressure and accordingly alters its position relative to the rollers.

The result is an irregular and uncommercial manufacture.

lt has also been proposed to secure the mandrel to a shaft placed at the inlet side of the machine whereby pressure on the mandrel or the mandrel shaft is avoided.

However, in these machines also it is not possible to realize the main condition for the production of a uniform product, which conslsts in maintaining the mandrel during the working period exactly in' its position between the rollers.

These defects of the known arrangements have been particularly noticeable in the manufacture of tubes of considerable length, asn

they `are now generally required.

Thepresent invention relates to machines in which the expanding is effected by means of a mandrel which is secured to a mandrel shaft placed on the inlet side of the machine and it is differentiated from the known ap paratus in that the mandrel shaft is ad justably arranged. A

In this manner, it is possible to maintain the mandrel always in a definite position between the rollers during the working period, and consequently to compensate for any alteration of the mandrel shaft.

The adjusting means may be of any suitable kind and be arranged at either end of the mandrel shaft. y

A coarse or fine adjustment of the mandrel may be provided. By the improved machine, the4 expanding of tubes of considerable length and constant dimensions presents no difficult-ies as the mandrel always maintains its definite position between the rollers.

Figure 1 is a longitudinal section showing one form of the invention,

\Fig. .2, is a longitudinal section through the mandrel controlling` means in another form of the invention in which a worm and worm-wheel is employed,

Fig. 3, is a longitudinal section through the mandrel controlling means in a third form of the invention, wherein coarse adjustment is obtained as\in Figure 1, .and fine adjustment is obtained by means of an eccentric,

Fig. 4, is a detail of the eccentric shown in Fig. 3,

Fig. 5, is a longitudinal section through the mandrel controlling means in another y Fig. 9, is a longitudinal section through the mandrel controlling means in another form of the invention.

Figure 1 sho ws a disc apparatus in plan in which roller discs a, which are relatively disposed in the known manner and, in conjunction with the mandrel b, effect the expansion of the tube. The mandrel shaft o, is. in this case, arranged on the entry side of the apparatus. To one eiid thereof, is

secured the mandrel b, its other end being connected to an adjusting device, which.4 consists of la screw-spindle d and mounted thereon a nut f, provided with a hand-wheel g, the said nut being rotatable but not axially movable in the frame e. With this construction, the mandrel shaft is not lsubjected to a bending but to a tensile stress. In this manner, even in the case of considerable lengths which exceed that of the tubeto be produced by about 1-2 metres a considerable reduction in the cross-sectional area of the mandrel shafts is effected, such shafts as hitherto used being subjected to pressure, and very heavy and therefore ineen' venient to handle. The mandrel shaft subjected to tension does. not alter its length 'in proportion to the roller pressure and retains the mandrel in the adjusted position under varying pressure. The adjustment o'f the mandrel is made .possible by the above described arrangement.

' a Worm z' actua-ted `motor.

Figures 3 and 4 Vshow a construction in which the coarse adjustment is again effected by the screw-spindle d, nut f, and handj wheelg. For the ine adjustment an eccentric k is provided, which is turned by the worm-wheel z' and Worm m.

In the construction shown in Figures 5 and 6, the adjustment is effected by levers o, pivoted to the frame at n, and engaging the tension rods p.. The rods p, are connected to a Icross-head g, which is provided with an interior screw-thread but is prevented from turning by connection with the frame e, and in which screw-thread there engages a sleeve t, which is exteriorly screw-threaded, is immovably secured to the frame e, and is provided with worm-teeth 1* engagingz the worm s. A spring u holds themandrel shaft housing lv, constantly in proximity to the lever o, so that an unintended backward movement of the mandrel shaft is avoided. The adjustment can alsol be effected by toggle levers or the like.

Figure 7 shows a. construction in which the mandrel shaft c, is adjustable first by a hollow screw-spindle w, provided with coarse threads by means of a Worm-wheel w, and a worm y, and then by a second screw-spindle z, With fine threads mounted in the first spindle fw. The rough adjustment of the mandrel-shaft is effected by means of the first-spindle lw, and the fine 'adjustment with the second spindle el In order to prevent the mandrel shaft taking part in the rotation of the mandrel during the Working operation, which causes a considerable additional expenditure of power and disadvantageousl affects the product, the mandrel is rotata. le with the least possible friction on the mandrel shaft, so that the latter is not rotatedtherewith. With mandrels, particularly those of greater d'1- ameter, the connection between mandrel and shaft can 'be e'ected by a sleeve on the outer surface of which is arranged the mandrel and which, by means of pressure ball-bear# ings, transmits the mandrel pressure to the mandrel shaft. A cooling and lubrication of the ball-bearin can be effected either during each pause 1n the rolling, or if the mandrel shaft be provided with a hole cool .-means can be arranged at each end of the mandrel-shaft.

Coarse adjustment may be made by fluid as illustrated in Fig. 9, but the use of fluid means is not specifically claimed herein.

By the displacement of the mandrel, the wall thickness can consequently be altered suitably even during the rolling operation. The mandrel can thus be designcdly ad'usted during the working operation in o er to obtain a tube of varying wall thickness at different parts and conse uently, for example, to produce a tube with an alternately` thickened or thin wall. j

Alterations in the wall thickne can also be effected by the combined displacement of the mandrel and the rollers. A

Claim to the method of produc-ing a tube of varying wall thickness is not being made herein, but a division of the present application is being filed in which this method is being disclosed and claimed.

I claim: v

, 1. In apparatus for expanding metal tubes, a mandrel shaftilocated at the inlet side of the apparatus, and a mandrel car ried by said shaft, in combination with means for giving rough adjustment to said mandrel and other means for giving fine adjustment to said mandrel.

2. In apparatus for expanding metal tubes, a vnut rotatably mounted at the inlet side of the apparatus and axially-immovable, a screw spindle operated thereby, and a mandrel shaft connected to the end oi the screw spindle, incombination with a mandrel carried b the mandrel shaft, rotation of said nut ing adapted to displace axially said screws indle and with it said mandrel shaft, there y adjusting said mandrel, and an eccentric and a worm .and worm-wheel for operating the same, said eccentric being adapted to give fine adjustment to said mandrel.

3. In apparatus for expanding metal tubes, a mandrel shaft located at the inlet side' of the apparatus, and a mandrel. carried by said shaft, in combination with screw means for giving rough adjustment to said mandrel, and other means for giving fine adj ustment to said mandrel.

In testimony whereof I have signed my name -to this specification.

lRUDOLF BUNGEROTH, 

